<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div {
            width: 200px;
            height: 200px;
            border: 1px solid red;
        }

        div:first-child {
            border-radius: 10px;
        }
        div:nth-child(2){
            border-radius: 100px;
        }
        /* 对角是一样的 */
        div:nth-child(3){
            border-radius: 20px 50px;
        }
        div:nth-child(4){
            border-radius: 20px 50px 100px;
        }
        div:nth-child(5){
            border-radius: 10px 40px 80px 100px;
        }
        div:nth-child(6){
            border-radius: 100px;
        }
    </style>
</head>

<body>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</body>

</html>